Used in immunological research to quantify interleukin-12 (IL-12 p40 subunit) levels in biological samples such as serum, plasma, or cell culture supernatants. Enables researchers to study immune responses, particularly in relation to T-cell activation and Th1 immune pathway involvement. Commonly applied in studies of autoimmune diseases, infectious diseases, and cancer immunotherapy to monitor cytokine expression and evaluate therapeutic interventions. Provides a sensitive and specific means to assess inflammation and immune modulation in experimental models involving rat subjects.